1. Technical Field
The present invention relates to mobile telecommunications and, more particularly, to an improved radio link addition procedure.
2. Discussion of Related Art
The radio link addition procedure is used in the 3rd Generation Partnership Project (3GPP) for establishing the necessary resources in the logical node (Node B) responsible for radio transmission/reception in one or more cells to/from the user equipment (UE). It does this by adding one or more additional radio links (RLs) toward a UE when there is already a Node B communication context for this UE in the Node B. Such is described, for instance, in 3GPP TS 25.433 v.4.0.0 (2001-03) “UTRAN Iub Interface NBAP Signaling (Release 4)” at Chapter 8.3 “NBAP Dedicated Procedures”, as well as in 3GPP TS 25.423 v.3.3.0 (2000-09) “UTRAN Iur Interface RNSAP Signaling” at Chapter 8.3.2 entitled “Radio Link Addition”. The procedure includes sending a radio link addition request from a serving RNC (SRNC) to a drift radio network controller (DRNC) and is concluded by the DRNC sending back a radio link addition response to the SRNC. Likewise, the radio link addition request is provided from a controlling RNC (CRNC) to the Node B in question, which in turn responds back to the CRNC with a radio link addition response.
At the present time, if a handover occurs from one RNC to another, and that handover is an inter-frequency handover, there is no way for the Node B to know whether or not the radio link is part of a first radio link set (RLS) established towards this UE. In other words, there is a need to know if the radio link should be considered part of the first RLS established toward this UE in the particular frequency to which the handover is directed. If it is, then there will be no uplink synchronization yet, and the Node B should be sending out a transmit power control (TPC) pattern appropriate in the circumstances. During interfrequency handover, Node B has to acquire synchronization again, as distinguished from soft handover, where synchronization does not have to be reacquired. The inner loop power control procedure, which is defined in 3G TS 25.214 v.4.0.0 (2001-03) at Chapter 5, is not utilized until uplink synchronization is achieved.